Presently, television receivers are being developed in the United States and elsewhere which can extract digital data nested in vertical interval. The uses of such data in a home viewing environment include their extraction and resultant display on the picture tube of news, weather, stock market items and the like.
In addition to these development efforts, there are other related developments underway to allow captioning of TV programs; in particular such captioning is useful to the deaf viewer or to a viewer who may have need of an alternate language than that being used by the performers on screen. These captioning systems require either special television receivers equipped with circuits for the vertical interval system previously referred to or may make use of an accessory unit to a standard television receiver. This accessory unit generally consists of an entire television receiver RF/IF/detector section so as to gain access to the demodulated video signals of the station being used. This is relatively expensive.
Accordingly, it is an object of this invention to provide improved means for the captioning of television programs.
It is another object of this invention to provide improved means for the captioning of television programs where such programs are received on standard television receivers and without making connections to the internal circuitry of the television receiver other than those reached through the antenna terminals.
It is a further object of this invention to provide means for the extraction of digital data telecast by a program origination source without making connections to the internal circuitry of the television receiver.
It is yet another object of this invention to provide means for the extraction of synchronization pulses related in phase to those being received by a television receiver so as to make these pulses available as a surrogate synchronization source in lieu of making connection to the internal circuitry of the television receiver.